Clay has long been used as a liquid absorbent, and has found particular usefulness as an animal litter.
Because of the growing number of domestic animals used as house pets, there is a need for litters so that animals may micturate, void or otherwise eliminate liquid or solid waste indoors in a controlled location. Many cat litters use clay as an absorbent. Typically, the clay is mined, dried, and crushed to the desired particle size.
Some clay litters have the ability to clump upon wetting. For example, sodium bentonite is a water-swellable clay which, upon contact with moist animal waste, is able to agglomerate with other moistened sodium bentonite clay particles. The moist animal waste is contained by the agglomeration of the moist clay particles into an isolatable clump, which can be removed from the container (e.g., litterbox) housing the litter. However, the clump strength of clay litters described above is typically not strong enough to hold the clump shape upon scooping, and inevitably, pieces of the litter break off of the clump and remain in the litter box, allowing waste therein to create malodors. Further, raw clay typically has a high clump aspect ratio when urinated in. The result is that the wetted portion of clay will often extend to the container containing it and stick to the side or bottom of the container.
What is needed is an absorbent material suitable for use as a cat litter/liquid absorbent that has better clumping characteristics, i.e., clump strength and aspect ratio, than absorbent materials heretofore known.
Another problem inherent in typical litters is the inability to effectively control malodors. Clay has very poor odor-controlling qualities, and inevitably waste build-up leads to severe malodor production. One attempted solution to the malodor problem has been the introduction of granular activated carbon (GAC) into the litter. However, the GAC is usually dry blended with the litter, making the litter undesirably dusty. Also, the GAC concentration must typically be 1% by weight or higher to be effective. Activated carbon is very expensive, and the need for such high concentrations greatly increases production costs. Further, because the clay and GAC particles are merely mixed, the litter will have GAC concentrated in some areas, and particles with no GAC in other areas.
The human objection to odor is not the only reason that it is desirable to reduce odors. Studies have shown that cats are territorial animals and will often “mark” litter that has little or no smell with their personal odor, such as by urinating. When cats return to the litterbox and don't sense their odor, they will try to mark their territory again. The net effect is that cats will return to use a litter box more often if the odor of their markings are reduced. Thus, a litter that is effective at eliminating or hiding a cat's personal odor can encourage the animal to use a litter box rather than depositing waste outside the box.
What is needed is an absorbent material with improved odor-controlling properties, and that maintains such properties for longer periods of time.
What is further needed is an absorbent material with improved odor-control, yet requiring much lower concentrations of odor controlling actives.
What is still further needed is an absorbent material with a lower bulk density while maintaining a high absorbency rate comparable to or exceeding heretofore known materials.
What is also needed is an absorbent material suitable for an animal litter which encourages animals to micturate and void on the absorbent material.